Re: Expansion symbolic

*To*: mathgroup at smc.vnet.net*Subject*: [mg74754] Re: Expansion symbolic*From*: "Dominic Jackson" <dr.kjackson at gmail.com>*Date*: Wed, 4 Apr 2007 03:54:52 -0400 (EDT)

Could anyone please tell me how to instruct Mathematica to expand the expression below with respect to the powers of x. I would like the constants c1,c2,c3 and c4 to stay behind the summation sign but the powers of x to cross over to multiply x^(k+i). (c1 (x^2) +c2 (x^3))* D[(Summation sign i=0 to infinity) Subscript[a,i+1][k] * x^(k+i),{x,2}]//Expand. This is what I get c1 x^2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] * x^(k+i-2) + c2 x^3 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] * x^(k+i-2) And this is what I want to achieve. c1 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] * x^(k+i) + c2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] * x^(k+i+1) Any clues. Thanx. Dom